cubicweb #676902 spécifier comportement cardinalité sur relation multiple [open]

for instance. in the expense cube we may wish to have:

  • Expense has_lines ExpenseLine en '+1'
  • Refund has_lines ExpenseLine en '+?'

currently, the 1 and ? are somewhat conflicting and isn't properly checked (and may be badly handled).

Define an expected behaviour, investigate needed fixes (integrity hooks).

prioritynormal
typeenhancement
done in<not specified>
load1.000
load left1.000
closed by<not specified>

Comments

  • 2010/02/09 10:03, written by acampeas

    imho cardinalities should be a relation type property

    • 2010/02/09 10:37, written by mailbot

      can't go that way unless by special casing attribute relation.

      • 2010/02/09 10:43, written by acampeas 
        because of the 1/? ambiguity ?

maybe 1/? cardinalities should be considered as "compatible" for this purpose (as could +/*) ?
        • 2010/02/09 10:58, written by mailbot

          no, because cardinality on relation type means that attribute 'name'
          should have the same cardinality for *all* entity types

          • 2010/11/10 16:33, written by acampeas

            Indeed.

            But attributes are special anyway; people rarely think of Foo.name and Bar.name as the same rtype (only sometimes, while typing some rql and almost by accident, does the genericity show up (as a good/practical thing)). Entities are a bit object-like and we tend to see them as namespaces.

            I have noted another discrepancy wrt attributes cardinality btw: Foo name String cardinality can be '11' or '?1'. But by analogy with relations, shouldn't it be '1*' / '?*' ?

            • 2010/11/10 16:41, written by sthenault

              semantically a final value can be linked to 1 and only 1 entity.

              • 2010/11/10 18:36, written by acampeas

                yes
                brain fart of mine

              • 2010/11/10 18:36, written by acampeas

                yes brain fart of mine

  • 2010/02/11 08:56, written by sthenault

    i think we should have a property on the relation type telling if subject/object cardinality are applied as a whole (hence should be consistent for each entity type) or for each relation definition. With a default to 'whole' on relations and 'each' for attributes for bw compat.

    In the example below, has_lines could have subjcardtype='whole', objcardtype='each'.

  • 2010/07/01 06:44, written by smarcu

    another example, we may wish to have:

    • X in_case Case -> 1?
    • Y in_case Case -> 1*
    • X in_case Case -> 1*

    Currently, X in_case Case -> 1? is not possible (error in operations which check cardinality during the commit)

add comment